One new type of imaging involves the capture of low intensity light—on the order of 103-1010 photons/sec/cm2/steradian—from a biological sample. A source of the light indicates a portion of the sample where an activity of interest may be taking place. In one example, the sample is a small animal such as a mouse and the light source could be tumor cells labeled with light emitting reporters such as firefly luciferase or fluorescent proteins or dyes. This technology is known as in vivo optical imaging.
Detection of light-emitting probes in-vivo within small living animals relies on the semitransparent nature of mammalian tissue, and requires complex instrumentation such as a high-sensitivity low-noise camera and advanced imaging software tools to interpret an image. The propagation of light through tissue is a diffusive process and therefore depends on the scattering and absorption properties of tissue. Advanced computer codes can localize a source of light in three-dimensions in tissue by simulating the photon diffusion process. This technique is often referred to as diffuse luminescent imaging tomography. Testing and development of such software often employs a living specimen, such as a real mouse, to verify accurate software results. In addition, purchasers of an imaging system often train new users on the system and/or software to build user familiarity. However, a living mouse is not an ideal subject for these instances. Careful handling requirements and the need for anesthesia make living mammals non-ideal for software development, software testing, and personnel training.
In view of the foregoing, the development of non-living models of light sources in tissue-like phantom materials would be desirable.